Which of the following biochemical cycles has a gaseous phase?

The hydrological cycle comprises two overlapping cycles.

Which of the following statements are correct?
$(a)$ Net primary productivity is available biomass for consumption to heterotrophs.
$(b)$ Secondary productivity is defined as the rate of formation of new organic matter by heterotrophs.
$(c)$ The annual net primary productivity of the ocean is greater than that of land.
$(d)$ Warm and moist environment favours decomposition.

Which group of living organisms given below is a link in the food chain between green plants and a hawk?

Give scientific reasons: Coral reefs are not found in the regions from West Bengal to Andhra Pradesh,but are found in Tamil Nadu and on the east coast of India.

$A$ frog,which feeds on insects,is a